A method and system for LR-FHSS dynamic frequency hopping for satellite-ground communication

Abstract

This invention provides an LR-FHSS dynamic frequency hopping method and system for satellite-to-ground communication. The method includes the following steps: obtaining the signal-to-noise ratio (SNR) value of each sub-channel and calculating the symbol error rate (BER) of the sub-channel based on the SNR value; arranging the sub-channels in descending order based on the BER to obtain a first sequence; interleaving the first sequence to obtain a second sequence; obtaining a candidate frequency hopping sequence set based on the second sequence; obtaining a preset reference signal sequence, wherein the reference signal sequence has a signal sequence segment set at the sequential position of each sub-channel in the candidate frequency hopping sequence; for each candidate frequency hopping sequence, flipping the corresponding signal sequence segment based on the BER of each sub-channel, and decoding the flipped analog sequence; calculating the packet reception rate (PAR) based on the decoding result; and determining the final frequency hopping sequence from the candidate frequency hopping sequence set based on the PAR.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to an LR-FHSS dynamic frequency hopping method and system for satellite-to-ground communication. Background Technology

[0002] In recent years, low-power wide-area network (LPWAN) technology has made significant progress, creating opportunities for digitalization around the world. LoRa, in particular, has been widely adopted due to its long-range connectivity and low power consumption. For example... Figure 2 As shown in (a), LoRa utilizes chirped spread spectrum (CSS) modulation to map data symbols to a linearly chirped initial frequency. LoRa also offers flexible bandwidth (BW) and spreading factor (SF) configurations to meet transmission requirements in different scenarios. However, LoRa also has drawbacks and limitations. Its transmission reliability is insufficient in complex environments or over ultra-long distances, and its dense deployment of LoRa networks is severely limited due to duty cycle constraints.

[0003] To address the performance degradation and capacity limitations of LoRa, existing technologies employ Long Range-Frequency Hopping Spread Spectrum (LR-FHSS), a wireless communication technology for satellite-to-ground communication. This technology further increases wireless coverage and capacity, supporting increasingly larger and denser network deployments and enabling direct connections between ground-based sensor nodes and satellites. Unlike LoRa, which uses CSS, a key feature of LR-FHSS is its use of Frequency Hopping Spread Spectrum (FHSS), which has proven to provide reliable communication even under interference. Specifically, LR-FHSS divides data into multiple segments and transmits them at different frequencies. Each data packet contains a header and payload at a different hop count. Each hop occurs in a sub-channel with a bandwidth of 488 Hz, significantly smaller than LoRa's 7.81-500 kHz bandwidth. At the same transmission power, the narrower bandwidth allows for better energy concentration, resulting in superior penetration capabilities. Therefore, LR-FHSS can maintain reliable long-range communication in satellite-to-ground interconnection scenarios. Figure 2(b) defines the bandwidth of the entire subchannel. The order of the subchannels used for all hops is represented as the Frequency Hopping Sequence (FHS). In each hop, LR-FHSS modulates each symbol using Gaussian Minimum Shift Keying (GMSK).

[0004] Although LR-FHSS can support networks with a wider range and greater capacity, it is still severely affected by dynamic channel interference during satellite-to-ground interconnection due to cloud cover or atmospheric absorption. Existing methods are not suitable for solving interference with LR-FHSS. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide an LR-FHSS dynamic frequency hopping method for satellite-to-ground communication to eliminate or improve one or more defects existing in the prior art.

[0006] One aspect of the present invention provides an LR-FHSS dynamic frequency hopping method for satellite-to-ground communication, the method comprising the following steps: Obtain the signal-to-noise ratio (SNR) value of each sub-channel, and calculate the symbol error rate (BER) of the sub-channel based on the SNR value; The sub-channels are sorted in descending order based on their symbol error rates to obtain a first sequence. The first sequence is then interleaved to obtain a second sequence. Based on the second sequence, a candidate frequency hopping sequence set is obtained, wherein the candidate frequency hopping sequence set includes candidate frequency hopping sequences with a number of sub-channels; A preset reference signal sequence is obtained. The reference signal sequence is configured with a signal sequence segment at the sequential position of each sub-channel in the candidate frequency hopping sequence. For each candidate frequency hopping sequence, the corresponding signal sequence segment is flipped based on the symbol error rate of each sub-channel, and the flipped analog sequence is decoded. The packet reception rate is calculated based on the decoding results, and the final frequency hopping sequence is determined from the candidate frequency hopping sequences in the candidate frequency hopping sequence set based on the packet reception rate.

[0007] Using the above scheme, the first sequence is obtained based on the symbol error rate of the sub-channel. Since continuous data transmission in the interference frequency band will cause significant transmission interference, interleaving is used to initially avoid the transmission interference caused by continuous data transmission in the interference frequency band. Furthermore, based on the symbol error rate of the sub-channel, the corresponding signal sequence segment is flipped, and the flipped analog sequence is decoded. Each candidate frequency hopping sequence can be flipped and decoded multiple times, and finally, multiple candidate frequency hopping sequences are filtered by packet reception rate, which further solves the channel interference problem and obtains the optimal transmission scheme.

[0008] In some embodiments of the present invention, in the step of calculating the symbol error rate of a subchannel based on the signal-to-noise ratio (SNR) of the subchannel, the symbol error rate of the subchannel is calculated based on the following formula: in, The symbol error rate of subchannel n is represented by the symbol rate of subchannel n. This represents the signal-to-noise ratio (SNR) of subchannel n. This indicates the preset calculation parameters. This represents the preset offset parameter, where e is a natural constant.

[0009] In some embodiments of the present invention, in the step of interleaving the first sequence to obtain the second sequence, an interfering sub-channel is determined based on a preset symbol error rate threshold, the number of interleaving columns is determined based on the number of interfering sub-channels, and the first sequence is interleaved based on the number of interleaving columns to obtain the second sequence.

[0010] In some embodiments of the present invention, the reference signal sequence is provided with multiple signal sequence segments corresponding to the number of sub-channels. The step of obtaining a preset reference signal sequence, wherein the reference signal sequence is provided with signal sequence segments corresponding to the sequential position of each sub-channel in the candidate frequency hopping sequence, and the step of flipping the corresponding signal sequence segment for each candidate frequency hopping sequence based on the symbol error rate of each sub-channel includes: The signal sequence segment corresponding to the sub-channel is determined based on the sequential position of the sub-channel in the candidate frequency hopping sequence; The number of characters that need to be flipped in the corresponding signal sequence segment is determined based on the symbol error rate of the sub-channel. The characters in the signal sequence segment are flipped based on the number of characters that need to be flipped.

[0011] In some embodiments of the present invention, in the step of determining the number of characters to be flipped for the corresponding signal sequence segment based on the symbol error rate of the sub-channel, the number of characters to be flipped for each signal sequence segment is calculated based on the following formula: The number of characters flipped = the total number of characters in the signal sequence segment The symbol error rate of the sub-channel corresponding to the signal sequence segment.

[0012] In some embodiments of the present invention, in the step of flipping the characters in the signal sequence segment based on the number of characters to be flipped in the signal sequence segment, a number of characters to be flipped are randomly selected from the characters in the signal sequence segment and flipped.

[0013] In some embodiments of the present invention, the step of calculating the packet reception rate based on the decoding result includes: For each candidate frequency hopping sequence, perform a preset number of flipping operations to obtain a preset number of simulated sequences. Decode each simulated sequence and record the number of times it is successfully decoded in the preset number of simulated sequences. The packet reception rate is calculated based on the number of times the packet is successfully decoded in a preset number of simulated sequences.

[0014] In some embodiments of the present invention, in the step of calculating the packet reception rate based on the number of times the simulation sequence is successfully decoded, the packet reception rate of each candidate frequency hopping sequence is calculated based on the following formula: Packet reception rate = Number of times successfully decoded in a preset number of simulated sequences / Preset number of times.

[0015] In some embodiments of the present invention, in the step of determining the final frequency hopping sequence from the candidate frequency hopping sequences in the candidate frequency hopping sequence set based on the packet reception rate, the candidate frequency hopping sequence with the highest packet reception rate is taken as the final frequency hopping sequence.

[0016] A second aspect of the present invention also provides an LR-FHSS dynamic frequency hopping system for satellite-to-ground communication. The system includes a computer device, which includes a processor and a memory. The memory stores computer instructions, and the processor executes the computer instructions stored in the memory. When the computer instructions are executed by the processor, the system implements the steps of the method described above.

[0017] A third aspect of the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the aforementioned LR-FHSS dynamic frequency hopping method for satellite-to-ground communication.

[0018] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and will also become apparent in part to those skilled in the art upon studying the text, or may be learned by practice of the invention. The objects and other advantages of the invention will become apparent from the description and the accompanying drawings.

[0019] Those skilled in the art will understand that the objectives and advantages achievable with the present invention are not limited to those specifically described above, and that the above and other objectives achievable with the present invention will become clearer from the following detailed description. Attached Figure Description

[0020] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, are not intended to limit the scope of the invention.

[0021] Figure 1 This is a schematic diagram of one embodiment of the LR-FHSS dynamic frequency hopping method for satellite-to-ground communication according to the present invention; Figure 2 A schematic diagram of the time-frequency signals of LoRa and LR-FHSS; Figure 3 This is a schematic diagram of the LR-FHSS transmitter's workflow. Figure 4 A diagram showing the comparison of PRR for the best and worst FHS; Figure 5 This is a schematic diagram showing the symbol error distribution when using different FHSs; Figure 6 A schematic diagram of the SER offset between model predictions and measurement results; Figure 7 This is a schematic diagram of the interlacing process; Figure 8 This diagram illustrates the changes in accuracy and operating costs. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. Here, the illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention.

[0023] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0024] Introduction to existing technologies: In existing wireless technologies such as Bluetooth and TSCH, frequency hopping is packet-level, meaning that a complete packet is transmitted in each channel. The decoding result of each packet depends only on the quality of the transmission channel. However, for LR-FHSS, which hops within each data packet, only a portion of the data packet is transmitted in each hop. The transmission of each hop affects the final decoding result of the entire data packet. Nodes transmitting in the same set of sub-channels but using different frequency hopping sequences (FHS) exhibit significantly different reliability performance. The key reason is that different FHSs lead to different symbol error distributions after deinterleaving. If the error distribution is clustered, forward error correction (FEC) will fail, and data packets will be dropped. Therefore, existing adaptive frequency hopping studies that only consider channel quality are insufficient for LR-FHSS; selecting the optimal FHS under dynamic interference is also necessary.

[0025] Existing technologies include blacklist-based adaptive frequency hopping methods. These methods identify poor channels using different metrics and prevent transmission on them. In Bluetooth, standard adaptive frequency hopping methods rely on Packet Delivery Ratio (PDR) or Received Signal Strength Indicator (RSSI) to estimate poor channels with high interference, then blacklist these channels and ignore them in subsequent frequency hopping sequences. In systems using TSCH, RSSI and PDR are used to indicate channel quality and disable poor channels. Some research also uses machine learning to estimate channels.

[0026] Disadvantages of existing technology: The blacklist-based adaptive frequency hopping method has two main drawbacks: First, frequency hopping in Bluetooth and TSCH is packet-level hopping, transmitting a complete data packet in each hop channel. The decoding result of the data packet depends only on the quality of the specific channel used. However, for LR-FHSS, the data payload is divided into multiple segments and transmitted in different channels. In addition to channel quality, FHS also affects the error patterns in the received data packets. Therefore, the above method, which does not consider FHS, is inefficient for LR-FHSS and cannot be applied to it. Second, LoRaWAN supports a large number of nodes connecting to a single gateway. The blacklist-based method can cause multiple nodes to select the same set of channels for transmission, and severe data packet collisions can lead to a decrease in the overall channel capacity.

[0027] In practical implementation, after the receiver receives the signal, it first performs GMSK demodulation to obtain symbols. SER is similar because the data packets are transmitted through the same sub-channel. However, after deinterleaving, the symbol errors of the two symbol streams using different schemes have different distributions, such as... Figure 5 As shown, Figure 5 In the text, Sub-CH represents a sub-channel, and Sub-CH1 to Sub-CH12 represent different sub-channels. Figure 5 The sign error ratio in (a) Figure 5 (b) The symbol error is more concentrated. Burst errors will exceed the error correction capability of convolutional codes and lead to more data packet loss. Therefore, this scheme improves the reliability of LR-FHSS by selecting a scheme.

[0028] In practical implementation, the data transmission workflow of the LR-FHSS transmitter is as follows: Figure 3 As shown.

[0029] The specific steps of this invention include: like Figure 1 As shown, this invention proposes an LR-FHSS dynamic frequency hopping method for satellite-to-ground communication, the steps of which include: Step S100: Obtain the signal-to-noise ratio (SNR) value of each sub-channel, and calculate the symbol error rate (BER) of the sub-channel based on the SNR value of the sub-channel. In the actual implementation process, the signal-to-noise ratio of each sub-channel is obtained through pre-measurement.

[0030] In practical implementation, to indicate the quality of each sub-channel, fine-grained hop signal-to-noise ratio (hopSNR) is used as an indicator. Using hopSNR has two advantages: First, the channel conditions of a sub-channel can be obtained by receiving only one data packet, thus enabling rapid adaptation to high dynamic interference; second, compared to the SNR of a data packet, using hopSNR allows for fine-grained estimation of each sub-channel. When the gateway receives an LR-FHSS packet, it decodes the data packet and then calculates the SNR of each sub-channel. The hopSNR is the SNR value of the sub-channel at each hop.

[0031] Step S200: Arrange the sub-channels in descending order based on the symbol error rate of the sub-channels to obtain a first sequence; perform interleaving processing on the first sequence to obtain a second sequence. In the specific implementation process, the first sequence can be 1, 2, 3, ..., m, where 1 corresponds to the sub-channel with the highest symbol error rate and m corresponds to the sub-channel with the lowest symbol error rate.

[0032] In the specific implementation process, in the step of interleaving the first sequence, if the number of columns to be interleaved is 5, then the interleaving process can be expressed as follows: Figure 7 As shown, the second sequence is .

[0033] Step S300: Based on the second sequence, a candidate frequency hopping sequence set is obtained, wherein the candidate frequency hopping sequence set includes candidate frequency hopping sequences with a number of sub-channels; In the specific implementation process, if the second sequence is 1, 6, 11, 3, 8, 5, 10, 2, 7, 12, 4, 9, then the candidate frequency hopping sequence can be obtained by including the candidate frequency hopping sequence one 1, 6, 11, 3, 8, 5, 10, 2, 7, 12, 4, 9, candidate frequency hopping sequence two 6, 11, 3, 8, 5, 10, 2, 7, 12, 4, 9, 1, and candidate frequency hopping sequence three 11, 3, 8, 5, 10, 2, 7, 12, 4, 9, 1, 6, which constitute a candidate frequency hopping sequence set.

[0034] The above scheme first obtains a first sequence based on the symbol error rate of the sub-channels, so that the sub-channels with high symbol error rates are all placed at the beginning of the first sequence. Then, the adjacent sub-channels are separated by interleaving to ensure that adjacent sub-channels are not used consecutively, thus preventing transmission errors caused by the continuous use of channels with high symbol error rates.

[0035] Step S400: Obtain a preset reference signal sequence. The reference signal sequence is configured with signal sequence segments at the sequential positions of each sub-channel in the candidate frequency hopping sequence. For each candidate frequency hopping sequence, the corresponding signal sequence segments are flipped based on the symbol error rate of each sub-channel, and the flipped analog sequence is decoded. In practice, each signal sequence segment may include 50 characters. If the number of sub-channels used is 12, the reference signal sequence will have a total of 600 characters.

[0036] In the specific implementation process, the decoding method for the simulated sequence can adopt existing decoding methods, which specifically include convolutional decoding processing and CRC verification steps.

[0037] Step S500: Calculate the packet reception rate based on the decoding result, and determine the final frequency hopping sequence from the candidate frequency hopping sequences in the candidate frequency hopping sequence set based on the packet reception rate.

[0038] Existing methods are inefficient in LR-FHSS because they only focus on selecting high-quality channels without adjusting the overall FHS, i.e. the overall scheme, which affects reliability. This scheme starts from the overall scheme and can better consider the reliability of the scheme.

[0039] Specifically, such as Figure 4As shown, interference was added to the first three sub-channels. All possible schemes were iterated, and nodes were allowed to transmit using the same set of sub-channels to determine the optimal and worst schemes that yielded the highest and lowest PRR, respectively. Figure 4 As shown, the average PRR of the optimal scheme is 0.89, which is 30.9% higher than that of the worst scheme. This is because using different schemes for the same sub-channel will produce different symbol error distributions, which will affect the error correction performance of Viterbi decoding in LR-FHSS. Therefore, this scheme reduces the channel transmission error caused by interference by selecting the final frequency hopping sequence.

[0040] Using the above scheme, the first sequence is obtained based on the symbol error rate of the sub-channel. Since continuous data transmission in the interference frequency band will cause significant transmission interference, interleaving is used to initially avoid the transmission interference caused by continuous data transmission in the interference frequency band. Furthermore, based on the symbol error rate of the sub-channel, the corresponding signal sequence segment is flipped, and the flipped analog sequence is decoded. Each candidate frequency hopping sequence can be flipped and decoded multiple times, and finally, multiple candidate frequency hopping sequences are filtered by packet reception rate, which further solves the channel interference problem and obtains the optimal transmission scheme.

[0041] In some embodiments of the present invention, in the step of calculating the symbol error rate of a subchannel based on the signal-to-noise ratio (SNR) of the subchannel, the symbol error rate of the subchannel is calculated based on the following formula: in, The symbol error rate of subchannel n is represented by the symbol rate of subchannel n. This represents the signal-to-noise ratio (SNR) of subchannel n. This indicates the preset calculation parameters. This represents the preset offset parameter, where e is a natural constant.

[0042] In the specific implementation process, It can be 2.9.

[0043] In the specific implementation process, based on existing research, the following descriptions are provided. and The theoretical model of the relationship between them can be expressed as: To demonstrate the efficiency of the theoretical model, this scheme collected LR-FHSS data packets. Nodes transmitted 20-byte packets at a center frequency of 868 MHz, with OCW, Code Rate (CR), and Transmission Power (TP) of 137 kHz, 1 / 3, and 14 dBm, respectively. This scheme calculated the actual SER of the data packets and compared it with the theoretical model of existing technologies. Figure 6 As shown, there is a gap between the theoretical model and the actual SER. Therefore, this scheme introduces an offset δ.

[0044] In practical implementation, the value of δ depends on the environment. To obtain δ, this scheme first receives data packets with different SNRs and calculates the corresponding SER, thus obtaining the optimal δ that minimizes the estimation error between the estimated SER and the actual SER. ,in The actual SER is calculated from packets received in a real environment, and the resulting δ is 2.9 dB.

[0045] In some embodiments of the present invention, in the step of interleaving the first sequence to obtain the second sequence, an interfering sub-channel is determined based on a preset symbol error rate threshold, the number of interleaving columns is determined based on the number of interfering sub-channels, and the first sequence is interleaved based on the number of interleaving columns to obtain the second sequence.

[0046] In the specific implementation process, before the step of determining the interfering sub-channel based on the preset symbol error rate threshold, the method further includes calculating the average symbol error rate of the sub-channel, using the average symbol error rate as the symbol error rate threshold, and if the symbol error rate of the sub-channel is higher than the symbol error rate threshold, then the sub-channel is determined to be an interfering sub-channel, and if the symbol error rate of the sub-channel is not higher than the symbol error rate threshold, then it is not an interfering sub-channel. If the number of interfering sub-channels is 5, then the number of columns for interleaving processing is determined to be 5.

[0047] By adopting the above scheme, this scheme can dynamically adjust the symbol error rate threshold, making it applicable to different channel environments and improving the applicability of the scheme.

[0048] In some embodiments of the present invention, the reference signal sequence is provided with multiple signal sequence segments corresponding to the number of sub-channels. The step of obtaining a preset reference signal sequence, wherein the reference signal sequence is provided with signal sequence segments corresponding to the sequential position of each sub-channel in the candidate frequency hopping sequence, and the step of flipping the corresponding signal sequence segment for each candidate frequency hopping sequence based on the symbol error rate of each sub-channel includes: The signal sequence segment corresponding to the sub-channel is determined based on the sequential position of the sub-channel in the candidate frequency hopping sequence; The number of characters that need to be flipped in the corresponding signal sequence segment is determined based on the symbol error rate of the sub-channel. The characters in the signal sequence segment are flipped based on the number of characters that need to be flipped.

[0049] In practice, the reference signal sequence is a signal sequence that can be completely and correctly decoded.

[0050] In some embodiments of the present invention, in the step of determining the number of characters to be flipped for the corresponding signal sequence segment based on the symbol error rate of the sub-channel, the number of characters to be flipped for each signal sequence segment is calculated based on the following formula: The number of characters flipped = the total number of characters in the signal sequence segment The symbol error rate of the sub-channel corresponding to the signal sequence segment.

[0051] In the specific implementation process, if the candidate frequency hopping sequence is 1, 6, 11, 3, 8, 5, 10, 2, 7, 12, 4, 9, then the sub-channel corresponding to sequence number 1 corresponds to the first signal sequence segment. If each signal sequence segment is 50 characters, then the sub-channel corresponding to sequence number 1 corresponds to characters 1-50, and the sub-channel corresponding to sequence number 6 corresponds to characters 51-100.

[0052] In some embodiments of the present invention, in the step of flipping the characters in the signal sequence segment based on the number of characters to be flipped in the signal sequence segment, a number of characters to be flipped are randomly selected from the characters in the signal sequence segment and flipped.

[0053] In the specific implementation process, if the symbol error rate of the sub-channel corresponding to sequence number 1 is 0.1, then 50*0.1=5 characters are randomly selected from the 1-50 characters for flipping. Specifically, if the character is 0, it is flipped to 1, and if the character is 1, it is flipped to 0.

[0054] Using the above scheme, random flipping can simulate the randomness of the environment, and this scheme performs multiple flipping processes on each candidate frequency hopping sequence, which can comprehensively evaluate the merits of the candidate frequency hopping sequence.

[0055] In some embodiments of the present invention, the step of calculating the packet reception rate based on the decoding result includes: For each candidate frequency hopping sequence, perform a preset number of flipping operations to obtain a preset number of simulated sequences. Decode each simulated sequence and record the number of times it is successfully decoded in the preset number of simulated sequences. The packet reception rate is calculated based on the number of times the packet is successfully decoded in a preset number of simulated sequences.

[0056] In some embodiments of the present invention, the preset number of times the flipping process is performed can be 200.

[0057] In the specific implementation process, this solution selects a preset number of flipping processes, such as... Figure 8 As shown, a large preset number of iterations K leads to higher time consumption and affects online selection, while a small preset number of iterations K results in lower accuracy of the Packet Reception Rate (PRR). Therefore, this scheme needs to achieve a good balance between accuracy and overhead. This scheme first collects LR-FHSS packets under different SNRs in a real environment and decodes them to obtain the actual packet reception rate as a baseline. Then, based on Monte Carlo simulation, the difference between the predicted PRR and the actual PRR is used as the error and the method's running time. The results are shown below. Figure 8 As shown in the figure. The results show that the running time increases linearly with the increase of K. When K>200, the error stabilizes, so K is set to 200.

[0058] In some embodiments of the present invention, in the step of calculating the packet reception rate based on the number of times the simulation sequence is successfully decoded, the packet reception rate of each candidate frequency hopping sequence is calculated based on the following formula: Packet reception rate = Number of times successfully decoded in a preset number of simulated sequences / Preset number of times.

[0059] In some embodiments of the present invention, in the step of determining the final frequency hopping sequence from the candidate frequency hopping sequences in the candidate frequency hopping sequence set based on the packet reception rate, the candidate frequency hopping sequence with the highest packet reception rate is taken as the final frequency hopping sequence.

[0060] In the specific implementation process, the hardware required for the algorithm implementation of this scheme is a software-defined radio system (SDR) and a commercial LR-FHSS node. The SDR is HackRF One. Each LR-FHSS node consists of two parts: an STM32L476RG as the processing module and an SX1262MB2CAS as the LoRa radio frequency module. This scheme uses MatLab language as the algorithm implementation language. The computer controls the HackRF One to receive the LR-FHSS. The computer calculates the final frequency hopping sequence and returns it to the LR-FHSS node through the downlink. The node uses the final frequency hopping sequence and performs the next transmission.

[0061] The beneficial effects of this plan include: 1. This scheme can dynamically adjust the transmission scheme, rather than simply blacklisting poor channels, thus improving the reliability of LR-FHSS and better achieving the stability of satellite-to-ground interconnection.

[0062] 2. This scheme uses hop SNR instead of the packet SNR used in existing methods to represent fine-grained conditions in sub-channels, and proposes an LR-FHSS PRR prediction model based on hop SNR and FHS.

[0063] 3. This scheme reduces the number of candidate FHSs by using an interleaved search algorithm, speeds up the search process, and can select the optimal transmission scheme online.

[0064] This invention also provides an LR-FHSS dynamic frequency hopping system for satellite-to-ground communication. The system includes a computer device, which includes a processor and a memory. The memory stores computer instructions, and the processor executes the computer instructions stored in the memory. When the computer instructions are executed by the processor, the system implements the steps of the method described above.

[0065] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the aforementioned LR-FHSS dynamic frequency hopping method for satellite-to-ground communication. The computer-readable storage medium can be a tangible storage medium, such as random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, floppy disks, hard disks, removable storage disks, CD-ROMs, or any other form of storage medium known in the art.

[0066] Those skilled in the art will understand that the exemplary components, systems, and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Whether implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention. When implemented in hardware, it can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this invention are programs or code segments used to perform the desired tasks. The programs or code segments can be stored in a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried in a carrier wave.

[0067] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0068] In this invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or in place of features of other embodiments.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations of the embodiments of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dynamic frequency hopping method for satellite-to-ground communication using LR-FHSS, characterized in that, The steps of the method include: Obtain the signal-to-noise ratio (SNR) value of each sub-channel, and calculate the symbol error rate (BER) of the sub-channel based on the SNR value; The sub-channels are sorted in descending order based on their symbol error rates to obtain a first sequence. The first sequence is then interleaved to obtain a second sequence. Based on the second sequence, a candidate frequency hopping sequence set is obtained, wherein the candidate frequency hopping sequence set includes candidate frequency hopping sequences with a number of sub-channels; A preset reference signal sequence is obtained. The reference signal sequence is configured with a signal sequence segment at the sequential position of each sub-channel in the candidate frequency hopping sequence. For each candidate frequency hopping sequence, the corresponding signal sequence segment is flipped based on the symbol error rate of each sub-channel, and the flipped analog sequence is decoded. The packet reception rate is calculated based on the decoding results, and the final frequency hopping sequence is determined from the candidate frequency hopping sequences in the candidate frequency hopping sequence set based on the packet reception rate.

2. The LR-FHSS dynamic frequency hopping method for satellite-to-ground communication according to claim 1, characterized in that, In the step of calculating the symbol error rate of a subchannel based on its signal-to-noise ratio (SNR), the symbol error rate of the subchannel is calculated using the following formula: in, The symbol error rate of subchannel n is represented by the symbol rate of subchannel n. This represents the signal-to-noise ratio (SNR) of subchannel n. This indicates the preset calculation parameters. This represents the preset offset parameter, where e is a natural constant.

3. The LR-FHSS dynamic frequency hopping method for satellite-to-ground communication according to claim 1, characterized in that, In the step of interleaving the first sequence to obtain the second sequence, an interfering sub-channel is determined based on a preset symbol error rate threshold, the number of interleaving columns is determined based on the number of interfering sub-channels, and the first sequence is interleaved based on the number of interleaving columns to obtain the second sequence.

4. The LR-FHSS dynamic frequency hopping method for satellite-to-ground communication according to any one of claims 1 to 3, characterized in that, The reference signal sequence is configured with multiple signal sequence segments corresponding to the number of sub-channels. The step of obtaining a preset reference signal sequence, wherein the reference signal sequence is configured with signal sequence segments corresponding to the sequential position of each sub-channel in the candidate frequency hopping sequence, and the step of flipping the corresponding signal sequence segment for each candidate frequency hopping sequence based on the symbol error rate of each sub-channel includes: The signal sequence segment corresponding to the sub-channel is determined based on the sequential position of the sub-channel in the candidate frequency hopping sequence; The number of characters that need to be flipped in the corresponding signal sequence segment is determined based on the symbol error rate of the sub-channel. The characters in the signal sequence segment are flipped based on the number of characters that need to be flipped.

5. The LR-FHSS dynamic frequency hopping method for satellite-to-ground communication according to claim 4, characterized in that, In the step of determining the number of characters to be flipped for the corresponding signal sequence segment based on the symbol error rate of the sub-channel, the number of characters to be flipped for each signal sequence segment is calculated based on the following formula: The number of characters flipped = the total number of characters in the signal sequence segment The symbol error rate of the sub-channel corresponding to the signal sequence segment.

6. The LR-FHSS dynamic frequency hopping method for satellite-to-ground communication according to claim 4, characterized in that, In the step of flipping the characters in the signal sequence segment based on the number of characters that need to be flipped, a number of characters that need to be flipped are randomly selected from the characters in the signal sequence segment and flipped.

7. The LR-FHSS dynamic frequency hopping method for satellite-to-ground communication according to claim 1, characterized in that, The step of calculating the packet reception rate based on the decoding results includes: For each candidate frequency hopping sequence, perform a preset number of flipping operations to obtain a preset number of simulated sequences. Decode each simulated sequence and record the number of times it is successfully decoded in the preset number of simulated sequences. The packet reception rate is calculated based on the number of times the packet is successfully decoded in a preset number of simulated sequences.

8. The LR-FHSS dynamic frequency hopping method for satellite-to-ground communication according to claim 7, characterized in that, In the step of calculating the packet reception rate based on the number of times the data was successfully decoded in a preset number of simulated sequences, the packet reception rate for each candidate frequency hopping sequence is calculated based on the following formula: Packet reception rate = Number of times successfully decoded in a preset number of simulated sequences / Preset number of times.

9. The LR-FHSS dynamic frequency hopping method for satellite-to-ground communication according to claim 1, characterized in that, In the step of determining the final frequency hopping sequence from the candidate frequency hopping sequences in the candidate frequency hopping sequence set based on the packet reception rate, the candidate frequency hopping sequence with the highest packet reception rate is taken as the final frequency hopping sequence.

10. An LR-FHSS dynamic frequency hopping system for satellite-to-ground communication, characterized in that, The system includes a computer device, which includes a processor and a memory. The memory stores computer instructions, and the processor executes the computer instructions stored in the memory. When the computer instructions are executed by the processor, the system implements the steps of the method as described in any one of claims 1 to 9.

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